The needle in some commercial electrospray ionization (ESI) sources is operated at kilovolt potentials during electrospray operation. For such ESI sources, a longer dielectric liquid transfer line of several inches is typically configured between the ground potential injector valve and the ESI needle to allow a gradual drop in kilovolt potential through the sample solution. A high electric field gradient in the transfer tube is avoided to minimize sample heating, electrophoretic and electrolysis effects during Flow injection analysis (FIA). Liquid transfer lines can be reduced in length when an ESI source in configured with a grounded needle, however, even with grounded ESI needles, the dead volume due to the transfer lines cannot be entirely eliminated. For ion mobility spectrometer (IMS) applications where small amounts of sample are available for injection, sample dilution or losses due to injector valve, connector and transfer line dead volumes and surfaces may compromise the limit of detection.